Copper vs Aluminum vs Ect.

[TheDukeAnumber1]

Quarter sized pump, is that including the motor? Also, are you making a white laser build? Very cool if you are.

 

[flare09]

yes i am going for the overkill here

and yes the whole pump fits in a quarter, i was thinking about upgrading to pump more but its slightly bigger, and if it moves to fast the water wont heat or cool enough.

i am going for a multicolor build yes. with an add-able spirograph

 

[TheDukeAnumber1]

I really don't think you can have a pump that moves the water too fast since there are no phase changes in your to be system. It will just spread the heat quicker.

 

[Cyparagon]

Aluminum forms an oxide on the surface with pretty bad thermal properties

Alumina has good thermal properties, sir. It is often used in thermal grease. Even if it wasn't, it's only 4 nanometers thick.

I would be running distilled deionized water... So there isn't really that much compression.

You mean no compression. Water doesn't compress, so you have zero temperature change when you apply or remove pressure from it.

 

[flare09]

no[/B] compression. Water doesn't compress, so you have zero temperature change when you apply or remove pressure from it.

well, very little. should i run the next best thing if i want to go for the compression? amonia, or something safer...ethyl glycol?

and should i speed up the liquid then, increase pump pressure, tubing sizing and just go all out?

 

[TheDukeAnumber1]

@Cyparagon
Relatively good, compared to Aluminum not really.
Aluminum = 237 W·m−1·K−1
Aluminum Oxide = 30 W·m−1·K−1
But yes the layer is so thin it's not worth worrying about.

@flare09
All liquids are conventionally not compressible. If your going with a liquid system go for a stable fluid with good heat capacity. If you really want compression you'll need a phase changing system.

 

[Blutquell]

Seems you guys like geeking out on thermal conductivity

Yes, we all know the numbers don't lie, and know copper overall manages heat better than just about everything else.
I was thinking however, how about the mixing of metals? If any sort of combination would pose an awkward benefit.

A copper module and a copper heatsink
A copper module and an aluminium heatsink
An aluminium module and a copper heatsink
An aluminium module and an aluminium heatsink?

Or am i just trying to find five sides in a square here and copper-copper is the obvious winner? I think i am, since i have never seen combinations in finished products, which may very well hide a reason behind it.
I don't know enough on the subject to draw definite conclusions tho lol.

 

[BShanahan14rulz]

You aren't to be looking at the conductivity of alumina, but rather the emissivity, or radiative properties of it, esp. in its most common form/application to aluminum.

 

[flare09]

Haha trying to find 5 sides in a square brings two things to mind, 4th dimensions, or a similarity in trying to understand women.

Well a bimetal imho would leave room for error. Press fitting the two together aesthetically it would be awesome. But there's also the fact, with aluminum and copper, expansion properties are different. Aluminum is much more. So one might crack or expand out or place.

Now, as has been stated, the diodes ideally aren't heating enough to cause these problems, but Imo a copper base in some aluminum fins would be kinda badass.


So collectively, everyone thinks I should drop the homemade radiator and an attempted condensing and expanding unit, and just put tue waterblock and TEC? I put alot of time into that little thing :/ bending tubes, making the fins, experimenting with alumaweld...

 

[Cyparagon]

If you're cooling a laser diode, you don't even need a water block. A CPU cooler is plenty.

Aluminum forms an oxide on the surface with pretty bad thermal properties ... compared to Aluminum

So you judge thermal conductivity of all materials in comparison with aluminum? That would mean virtually everything except precious metals and diamonds have bad thermal conductivity. The material sciences world disagrees with you.

 

[TheDukeAnumber1]

So you judge thermal conductivity of all materials in comparison with aluminum? That would mean virtually everything except precious metals and diamonds have bad thermal conductivity. The material sciences world disagrees with you.

Well, everything is relative to your application. When using an aluminum heat sink, where aluminum oxide forms on the surface, the oxidized the surface layer's thermal conductivity drops to about 13% of what it used to be as aluminum, which is crappy, but negligible in this case. Why no one is trying to make a sink out of aluminum oxide. Compare thermal grease/epoxy to actual metals and it sucks, compare to non thermal grease/epoxy and it's great.

It should be obvious at this point that's we're talking about laser heat sinking materials, and not judging all materials against aluminum.

@flare09

Hey if you want to go above and beyond and make something cool and functional even if it only ends up being a concept project then go for it.

 

[flare09]

Quote: @flare09

Hey if you want to go above and beyond and make something cool and functional even if it only ends up being a concept project then go for it.

Thanks. Lol im going to the shop tomorrow. I probably have a few more visits before the host is done. But ill make a thread when it is

 

[Encap]

Maybe gold plate the copper to resist corrosion--no nickel layer in between just gold on copper. Do not worry about diffusion of copper into the gold---at room temperatures that will take longer than the finished products lifetime.

 

[Blutquell]

lol xD

 

[grainde]

Hey just to thow something else into the mix...A few have mentioned that Ag is better than Cu and Al. Whilst this is true in terms of the thermal conductivity, it isnt in terms of its specific heat capacity (S). Silver actually has a lower S than either Al or Cu, so even though it has a much higher density than Al, and a slightly higher density than Cu, this isnt enough to off set its lower S. For the same amount of energy input (with a fixed volume heatsink) Ag actually runs slightly warmer than Al, but only around 1%! This means that Cu would still out perform an Ag module in keeping the temperature of the diode lower. :beer:

 

[TheDukeAnumber1]